Why can creating a static const std::string cause an exception?

Question

I have string constants, for strings that I use in multiple places in my app:

namespace Common{     static const std::string mystring = "IamAwesum"; } 

When posting a question about something else (What happens to a .h file that is not included in a target during compilation?), another user made the following comment :

be aware that your static string are global in this case. So they are could create an exception at anytime and can't be catch. I advise you to use function who return a reference of your string. std::string const &mystring { static std::string const mystring = "IamAwesum"; return mystring} by this way your object is only construct when needed

Can someone explain why using static const strings in the manner that I do so above, risks throwing exceptions ?

Answer 1

N4140 § 3.6.2 [basic.start.init]/ 4

It is implementation-defined whether the dynamic initialization of a non-local variable with static storage duration is done before the first statement of main.

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N4140 § N4140 15.3 [except.handle]/ 13

Exceptions thrown in destructors of objects with static storage duration or in constructors of namespace-scope objects with static storage duration are not caught by a function-try-block on main().

You simply cannot catch an exception generated by the string's constructor - say, std::bad_alloc.

(opinion) That being said, for such small strings I find this kind of consideration to be paranoid.